Optical pulse propagation at negative group velocities due to a nearby gain line

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Physical Review A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.49.2938· OSTI ID:5017705

Bolda, E L; Garrison, J C; Chiao, R Y ^[1]

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1. Department of Physics, University of California, Berkeley, California 94720 (United States)

For a pulse with carrier frequency detuned less than an atomic plasma frequency but outside a narrow Lorentzian gain line, the group velocity will be negative. Unlike propagation at the center of an absorption line, the energy velocity is approximately equal to the group velocity, and is also negative. We show that a classical Gaussian pulse with such a carrier frequency will propagate at the negative group velocity for many atomic plasma wavelengths, before dispersion deforms the pulse shape. The peak of the transmitted pulse leaves the gain medium before the peak of the incident pulse enters, i.e., the pulse is transmitted superluminally. For a sufficiently long medium the exit pulse is well resolved from a comparison pulse traveling through an equal distance of vacuum. There is no conflict with causality, as numerical simulations with a switched-on Gaussian demonstrate. We propose an experiment to observe this kind of propagation by sending a pulsed probe beam through a Xe gas cell pumped to achieve inversion.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5017705
• Journal Information: Physical Review A; (United States), Journal Name: Physical Review A; (United States) Vol. 49:4; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

661100 -- Classical & Quantum Mechanics-- (1992-)
661300* -- Other Aspects of Physical Science-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLIFICATION
EXPERIMENT PLANNING
GAIN
OPTICAL DISPERSION
PLANNING
POPULATION INVERSION
VELOCITY
WAVE PROPAGATION